What famous building in England is an example of English architecture?
This rather depends what you are looking for. The English have been building for so long, some of our older buildings like Norman castles (Tower of London) and cathedrals are a thousand years old. Building styles changed over the centuries, from the wooden framed rustic looking Tudor style, Gothic cathedrals and neo-Gothic buildings like the Houses of Parliament, beautiful formal Georgian terraces like the one in Bath, Sussex thatched cottages, Victorian urban terraces, beautiful cotton mills like cathedrals, the Byzantine Westminster cathedral, Wren’s St Paul’s, London’s baroque County Hall, the modernist SIS/MI6 building, the variation is too great to list here.
Your question is too broad. There isn’t actually a school of English Architecture. There are many famous and prominent English buildings that are examples of other schools of architecture. Big Ben and the Parliament building are both very famous examples of Neo-Gothic architecture that are in London, for example.